there are tons of the them out there like keywordcomplete and keywordspy. you just need to do a search on google. i don't know of any that are free but that doesn't mean there aren't any.
As others have said there are a number of tools that help with competitive intelligence. Here is a list that will get you started with some tools - http://www.webmaster-elements.com/webmaster-tools/competitive-analysis-tools.htm HTH
Look at their meta description, meta keywords and page title. You can do this by viewing the source code of their page. In your browser, go to view - page source. There are no special tools required.
PPC Web Spy claim that it can find out your competitor keywords. You can google it, it's available to download for free.
I have had great sucess with Spyfu, it gives you pretty accurate information and helps you decide a course of action against your competitors.
Input their website in the google adwords keyword tool and see what terms come up as competitive terms.
If you can't find anything, start a "campaign" in adwords. Google gives you all the keywords that are used. Then start typing them in to see if your competitors are there.